@adamaero This is what my response was to that comment:
I didn't just "hand out" the solution - I explained why OP is wrong and how, and explained how to get to the answer, while linking OP to helpful resources and further reading on the subject. Also, as OP said, it's not a homework question, but rather an example they don't understand from their teacher's notes, so even if I did "hand out" a solution, no harm is done